73. A reserve for public purposes shall remain in force for an initial term of two years and, on renewal, for a term of two more years; it shall then remain in force, as long as it is not abandoned or cancelled or the property affected is not expropriated, for an indefinite term which, in conjunction with the first term and, where such is the case, the renewal term, shall not exceed ten years.
The formalities and procedures required by this act for the establishment of a reserve shall apply to its renewal.